Papers in Meteorology and Geophysics
Online ISSN : 1880-6643
Print ISSN : 0031-126X
ISSN-L : 0031-126X
Volume 32 , Issue 3
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  • Tokunosuke Fujitani
    1981 Volume 32 Issue 3 Pages 119-134
    Published: 1981
    Released: March 09, 2007
    JOURNALS FREE ACCESS
       In order to investigate the turbulent transport processes in the marine boundary layer, the direct measurement of turbulent fluxes of momentum, sensible heat and water vapor by the eddy correlation method was carried out aboard the R. V. Keifu-Maru over the East China Sea during the AMTEX field programs.
       It has been well known that the eddy correlation method is the most reliable means for turbulent flux measurement, but is considered to be difficult of application to shipboard measurement. This difficulty has recently been overcome by the correction technique, which was developed and applied to the pre-AMTEX test cruise by the present author (Mitsuta and Fujitani, 1974).
       In the present study some improvement of the correction technique was achieved to make the wind velocity correction more precise. Fluctuations of wind velocity components, air temperature and specific humidity, and motion of the ship were measured aboard the ship and turbulent fluxes were obtained by the eddy correlation method throughout the AMTEX observational periods in 1974 and 1975.
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  • Tomoaki Yoshikawa
    1981 Volume 32 Issue 3 Pages 135-148
    Published: 1981
    Released: March 09, 2007
    JOURNALS FREE ACCESS
       In order to represent or predict concentrations of air pollutants continuously, a finite difference model was offered to solve the nonlinear diffusion equation on the assumption that variable winds and diffusion parameters were given in all meshes at any time in some way. Insecurities and errors of finite difference calculation were avoided with adopting Lax-Wendroff method for horizontal transfer, backward step for vertical transfer, forward step for horizontal diffusion and Clank-Nicolson method for vertical diffusion after examination of various difference schemes. Restrictive conditions were confirmed also for steps of time and space.
       Verification of the model was conducted with comparison between analytical solutions of the diffusion equation for uniform wind and constant diffusion coefficients in the field and numerical solution for the same wind and diffusivity. As an analytical solution, a puff model was adopted for calm and breezy conditions and a plume model was used for windy condition.
       The verification in various stability categories showed sufficient accuracy to justify practical use, except a few cases that the concentration peak with the numerical model distributed slightly flatter than that with the puff model in the limited periods of breezy condition. Noise undulations in the leeward boundary and their extensions to windward in windy condition were removed with such a regulation that Δc/Δx≈0 was satisfied in the leeward boundary.
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  • Fujio Kimura, Tomoaki Yoshikawa, Junji Sato
    1981 Volume 32 Issue 3 Pages 149-154
    Published: 1981
    Released: March 09, 2007
    JOURNALS FREE ACCESS
       Concentration of NOx was measured several tens of meters downwind from a continuous NOx source by the fast respondent analyzer. Horizontal and vertical distributions of averaged NOx concentration were also measured in the same periods using bag samplers.
       The frequency distribution of instananeous concentration observed on the mean plume axis agrees well with the sharp cut off power low given by Gifford's fluctuating plume model. But the discontinuity of the frequency distribution at the maximum concentration is not sharp. It was confirmed that the frequency distribution of concentration averaged over a short period within 200 sec also followed Gifford's model.
       The ratio of the maximum short period concentration to the long period (2,700 sec) concentration was about 5 to 1 when the averaging time of the short period was 4 sec. The ratio descreases with the averaging time until about 100 sec. It becomes almost independent of the averaging time and not so different from 1 when the averaging time is longer than 100 sec.
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  • Junji Sato, Fujio Kimura, Tomoaki Yoshikawa
    1981 Volume 32 Issue 3 Pages 155-162
    Published: 1981
    Released: March 09, 2007
    JOURNALS FREE ACCESS
       In order to obtain the physically detailed atmospheric turbulent diffusion process, a series of short range diffusion experiments has been conducted in the atmospheric surface layer by using NOx gas as air tracer. This experiment includes an instantaneous point source and an continuous point source. The method and technique of this experiment are reported here and part of the analysis of diffusing puffs is discussed.
       Though various patterns of concentration distribution of diffusing puffs were observed, the most interesting feature was the trail of concentration of diffusing puffs. Seeing that the trail of a puff was not observed in spite of the existence of vertical wind shear, it was conjectured that the trail of a puff was not affected directly by vertical wind shear, and might be subject to the influence of some characteristics of turbulence.
       It was shown that the growth of σx was better expressed by travel time induced from mean wind speed by the sonic anemometer-thermometer. And the relation σx(t)∝T1.1 was obtained.
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  • Yukio Sugimura, Masaru Mayeda
    1981 Volume 32 Issue 3 Pages 167-171
    Published: 1981
    Released: March 09, 2007
    JOURNALS FREE ACCESS
       A more rapid and precise method than hitherto of determining uranium in sea water is described. The separation of uranium is done by adsorption on chelating resin in weak acid media with equilibrium batch method instead of chromatographic method as previously used. The determination of uranium is done by alpha-spectrometric method using 232U tracer and spectrophotometric method using uranyl-Arsenazo complex. The average recovery by this improved method is 100% and the standard deviation of the analytical result is below 2%.
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  • Michio Takahashi
    1981 Volume 32 Issue 3 Pages 173-181
    Published: 1981
    Released: March 09, 2007
    JOURNALS FREE ACCESS
       A strong-motion seismograph with a wide frequency band and large dynamic range has been required these days, for example, in the current international programs to deploy strong-motion earthquake instrument arrays. The pendulum motion of the so-called servo-type accelerometer is examined to show that this type of accelerometer is of use as a transducer for the strong-motion seismograph. Comparative observation was performed between an ordinary high sensitive long-period transducer and low-cost commercial product JA-4 (a kind of servo-type accelerometer which covers 0-500 Hz and until±2000 Gal). When the surface wave from the Iran earthquake on September 16, 1978 (Ms: 7.4) was observed at Tokyo, quite similar seismograms were obtained because the recording system had been designed so that both frequency responses should become approximately equal. On the basis of the assumption that slight differences between the seismograms are due to a lack of resolution of JA-4, its minimum detectable signal is found to be less than 0.15 mGalo-p in the low frequency band. Therefore, it can be said that this accelerometer is effective as a strong-motion seismograph.
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  • Shunji Konaga, Hiroshi Ishizaki
    1981 Volume 32 Issue 3 Pages 183-192
    Published: 1981
    Released: March 09, 2007
    JOURNALS FREE ACCESS
       From 14 September to 10 October, 1978, seven crossings (once in three days in principle) were made by the Seasat altimetry over the Kuroshio south of Honshu, Japan. These observations of the sea surface height by the Seasat-1 altimeter were compared with the dynamic topography charts taken in middle and late September on board the R. V. Takuyo of the Japan Maritime Safety Agency and in early and middle October on board the R. V. Shumpu Maru of the Kobe Marine Observatory.
       It may be seen that the variations of the Kuroshio flow path deduced from the altimetry have strong resemblance to those obtained from hydrographic observations, except for a systematic shift of the absolute values, probably due to incomplete corrections for the wet contribution, significant wave height, and so on.
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